UNKNOWNvSOLDIER

So my wifes appointment is on Dec 6th, and she was curious about a few things. First off are bags allowed in the Embassy, and if not what would be the most appropriate way to carry all of her documents into the embassy? Also, what dress attire is appropriate, ie Flipflops ect.

If my wife gets approved at her interview, does she get the stamp or whatever it is you get when you're approved, or do they take your passport and return it at a later time?

Why would she need an NBI?

Ok, so my wife went to go get an updated passport with you married name, and they told her that she needs the Certificate of Attendance from the CFO. My question is, what paperwork does she need to just get the certificate. She doesn't need the sticker and shes not leaving the country yet. I haven't even sent off the I-130 yet. There seems to be no info on what exactly she needs just for the certificate. Help guys! Thanks.